Wireless communication devices have become smaller and more powerful in order to meet consumer needs and to improve portability and convenience. Consumers have become dependent upon wireless communication devices such as cellular telephones, personal digital assistants (PDAs), laptop computers, and the like. Consumers have come to expect reliable service, expanded areas of coverage, and increased functionality. A wireless communication device may be referred to as a mobile station, an access terminal, a remote station, a user terminal, a terminal, a subscriber unit, user equipment, etc. The term “mobile station” will be used herein.
A wireless communication system may provide communication for a number of cells, each of which may be serviced by a base station. A base station may be a fixed station that communicates with mobile stations. A base station may alternatively be referred to as an access point, a Node B, or some other terminology.
A mobile station may communicate with one or more base stations via transmissions on the uplink and the downlink. The uplink (or reverse link) refers to the communication link from the mobile station to the base station, and the downlink (or forward link) refers to the communication link from the base station to the mobile station. A wireless communication system may simultaneously support communication for multiple mobile stations.
As used herein, the term “diversity” refers generally to the various methods that are available for providing a receiver with uncorrelated renditions of a signal of interest. There are many ways that diversity methods may be implemented. For example, in some wireless communication systems, the signal of interest may be redundantly transmitted over two (or possibly more) antennas to provide transmit diversity. Due to multipath and other phenomena, the transmitted signals may experience different path conditions and may arrive at the receiver at different times.